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I am in the process of setting up a dust extraction system for my workshop. The vital bit is a cyclone, which discharges sawdust into a bin, hooked up to a vacuum cleaner which collects the dust. It's a pretty conventional setup. There are los of videos on u tube.

However, I bought a vacuum cleaner online. It's rated noise level was stated to be 48 dB. This seemed excellent, as most vacs are in the 70 to 80 range, and on a logarithmic scale, that's quite a difference.

However, as I should have known, if something seems to good to be true, it probably is.

When I fired it up, I didn't need sophisticated measuring devices to tell me it was way over 48.

So I am stuck with it and will try to incorporate it as originally intended and have started to look at sound attenuation.

The plan is to place the cyclone, vac and sawdust bin in a cabinet underneath a bench.

I am dealing with airborne noise as well as direct vibration.

Having done some research, it's not clear to me if it's mass, in the form of a sturdy cabinet, or special sound- deadening foam- as used in recording studios, that I need, or both.

If any members have experience of this, I would appreciate your advice.

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Posted (edited)

Put it outside mounted on a post or stand secured to the ground, not your shop, place it where you will have minimum bends on the suctions side, build a shelter around it with easy access for upkeep and cleaning. No point in taking up space inside, wiring with an inside switch should be easy and the hole for the suction pipe should not be a problem either, just use foam or rubber to seal, don't want hard contact with the structure. Enjoy your quiet and cleaner work space.

Edited by jud

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7 hours ago, jud said:

Put it outside mounted on a post or stand secured to the ground, not your shop, place it where you will have minimum bends on the suctions side, build a shelter around it with easy access for upkeep and cleaning. No point in taking up space inside, wiring with an inside switch should be easy and the hole for the suction pipe should not be a problem either, just use foam or rubber to seal, don't want hard contact with the structure. Enjoy your quiet and cleaner work space.

Thanks jud, unfortunately I can't put it outside. I'm in a French town with 600 thick stone walls  and fierce planning regs. As I said, I'm still not clear if it's mass or absorption or both that I need need to be really effective. If I put it in a brick box for example, as generators sometimes are, I'm sure that's more effective than a ply one, but recording studios use special profile foam, not just polystyrene.The answer is probably both. On, on

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Have seen walls made soundproof by double studding. Each side had it's own support 2 X 4 studding sitting on the same 2 X 6 sill. The studs were evenly spaced but alternating sides, so a sound absorbing curtain could be woven between them, when in place each side was finishing to match the rest of the structure, just 2" thicker than the 2 X 4 walls. Might be able to duplicate the effects of such a wall, using double boxes separated by, a curtain. The discharge air could be muffled by a series of furnace filters or filter material stacked inside a large tube made to fit your space and allowing a muffled  depressurization your vacuum container inner box. Like most things, different ways to get the job done. Good Luck.

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As part of researching noise levels in my workshop, I came across noise- measuring apps online.Some of these are free. While they are not really the equivalent of professional noise- level meters, they are perfectly adequate for my purposes. My iPad now becomes my meter.

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Posted (edited)

Is a there closet in your workshop?  Insulate it well and put the equipment in there. Otherwise you'll have to build an enclosure. 

Edited by mtaylor

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Posted (edited)

Thanks Mark. As I said earlier, it's not clear to me if it is mass, in the form of a sturdy container, ( brick, plasterboard etc.), or absorption in the form of special foam , ( or some combination of both,) that will be most effective to reduce both airborne sound and direct vibration.  Putting this kit in a foam- lined box of some sort will obviously lower noise levels, but as this will run for long periods, I'm keen to make it as efficient as possible. Seems to be a lot of conflicting info out there. Research continues.

Edited by Williamo

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Absorptive material inside the box will be the key to sound deadening.   One thing you might do is go here:  https://sawmillcreek.org/forum.php.   I use the laser forums a lot for info.   The users are very helpful.  You may have become a "user" and register.  But a search on "dust extractor"  should give you lots of hits.  

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Maybe it would just be better to bite the bullet and get a quieter vacuum!

By the time you finish the suggested installation you'll probably spend about as much as a new machine would cost...never mind the work. And would the installation even work as well?

 

Then you might sell the one you have now

 

Chazz

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I used an old Sears 16 gal shop vac for years - It was really loud - had to use

sound suppressing head phones with it.  When the motor started arching, I

retired it to the dump.  Following discussions here I bought a Festool Midi.

Since I use a cyclone trap - the capacity of the unit is not important and the

smaller foot print was an advantage.  It is quiet enough, and pulls enough air,

but it turns itself off after a short run time.  A total waste of $600.

Looking around, I found a Rigid 14 gal at Home Depot for $100 that is about as 

quiet.  I no longer need the head phones.  It stays on just fine.  The only occasional

problem = I live in a condo and I think at least one neighbor has a garage door remote

that uses the same frequency as my on/off remote for the vac.  I have to make sure to

unplug it when I am done.

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Jaager,

 

If it works both ways, you could have a lot of fun opening their garage door with your shop vac.....

 

;)

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A side swipe lighting strike burned out the circuit board on my garage door opener and I have

never placed it.  I manually open the door and unlike most, I do keep my car in the garage -

I live on The Bay - Little Creek harbor actually - the salt water could maybe rust my car. I

do not mind the exercise.  So I don't know if the frequencies are the same - and an ironic factor

is that my car has the ability to produce the activation signal.

 

I was hoping someone knew why the Festool will not run continuously.  It acts as though the

overheat protection control is set at too low a temp.

It is not the RF switch.  If it because of the cyclone trap ( the Wood Craft salesman said

that Festool nixed a custom cyclone trap for their machines) then it really is an unacceptable machine. 

Pointless to test that since I will never not have the cyclone trap in-line.  The clogged filter and

quickly full bag with a vac only system = too much hassle.

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On 6/13/2018 at 5:58 PM, Chazz said:

Maybe it would just be better to bite the bullet and get a quieter vacuum!

By the time you finish the suggested installation you'll probably spend about as much as a new machine would cost...never mind the work. And would the installation even work as well?

 

Then you might sell the one you have now

 

Chazz

I did think of that and may do it but in any case the vac noise needs to be reduced.My current household vac is 80 dB. Too loud to run for long periods, especially while other kit is running.

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On 6/13/2018 at 8:07 AM, mtaylor said:

Absorptive material inside the box will be the key to sound deadening.   One thing you might do is go here:  https://sawmillcreek.org/forum.php.   I use the laser forums a lot for info.   The users are very helpful.  You may have become a "user" and register.  But a search on "dust extractor"  should give you lots of hits.  

Thanks for the Sawmill Creek connection. Very helpful.

As I said , reading noise reduction fora tells me the whole noise issue seems poorly understood, esp the relationship between mass and absorption. Research continues.

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Posted (edited)

I'm about to give up on general noise attenuation in the workshop as its going to be much simpler and cheaper to invest in some high-end ear protectors.

With some of my machines its almost impossible to economically reduce their noise output.

BTW if you are interested in the sound levels in your work area, take your own measurements. Values given by manufacturers are generally not the product of standardised testing, and are not tested while being used.

 

I am currently trying to source 65 mm dia. aluminium blast-gates and actuators. 100 mm seems to be the smallest I can find. I have used plastic ones before, but with mixed success. Any help would be much appreciated. Ball valves are also a possibility.

 

Edited by Williamo
incomplete

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Several years ago I built a sound reducing box for a compressor to be used at trade shows.  I used the best rated sound absorbing rigid foam and batting I could find, but the main way sound escapes is through vents needed to feed air to the compressor (with a vacuum, the air has to get out) and other cracks.   I ended up building a box with a double bottom so that the sound had to go through a bit of a zig-zag maze, somewhat like a Dorade vent.  The double bottom also reduced the transmission of mechanical vibration.   The maze was filled with batting, and the air inlet, made up of many small holes, faced the floor.  Other than those holes, the box was sealed.  Fortunately, for this application, the compressor didn't run often, so I didn't have to worry about heat from the compressor.  Since a vacuum doesn't generate much heat, this shouldn't be a problem.

 

Avoid large, flat panels, unless they are very rigid.  If it vibrates, it is basically a large surface to excite the air, just like the sound board of a guitar.

Use foam, especially egg-crate foam, or batting on the inside surfaces to absorb (damp) sound and avoid reflections off of hard surfaces.  To some extent, a soft covering on the outside panels also helps to deaden sound.   That's one of the reasons the inside of cars are carpeted or are covered with a hard foam (the other reason being to reduce injury in a crash).

 

As a last though, I wonder if putting a long hose on the air exit of the vacuum would help to contain the noise.

 

 

 

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10 hours ago, lehmann said:

Several years ago I built a sound reducing box for a compressor to be used at trade shows.  I used the best rated sound absorbing rigid foam and batting I could find, but the main way sound escapes is through vents needed to feed air to the compressor (with a vacuum, the air has to get out) and other cracks.   I ended up building a box with a double bottom so that the sound had to go through a bit of a zig-zag maze, somewhat like a Dorade vent.  The double bottom also reduced the transmission of mechanical vibration.   The maze was filled with batting, and the air inlet, made up of many small holes, faced the floor.  Other than those holes, the box was sealed.  Fortunately, for this application, the compressor didn't run often, so I didn't have to worry about heat from the compressor.  Since a vacuum doesn't generate much heat, this shouldn't be a problem.

 

Avoid large, flat panels, unless they are very rigid.  If it vibrates, it is basically a large surface to excite the air, just like the sound board of a guitar.

Use foam, especially egg-crate foam, or batting on the inside surfaces to absorb (damp) sound and avoid reflections off of hard surfaces.  To some extent, a soft covering on the outside panels also helps to deaden sound.   That's one of the reasons the inside of cars are carpeted or are covered with a hard foam (the other reason being to reduce injury in a crash).

 

As a last though, I wonder if putting a long hose on the air exit of the vacuum would help to contain the noise.

 

 

 

Thanks for your thoughts and practical suggestions. As I said in the post above, I'm giving up for the moment, and will address the problem later. I got a bit sidetracked with noise levels while designing a dust extraction system for my new work area- noise and dust being the two most important health considerations I want to sort out.

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